• Heat your oven to 325℉. Line your pan with parchment paper if you are using it, then butter your pan or parchment.

Graham cracker crust

• Add the graham crackers to your food processor and blitz until they have been turned completely into crumbs.
  14 (218 grams) full-sheet graham crackers
• Add the sugar and blitz to mix. Then add the melted butter and blitz to thoroughly combine.
  ¼ cup (55 grams) well-packed dark brown sugar, 6 tablespoons 85 grams unsalted butter
• Press the graham cracker cookie crust thoroughly into the prepared pan and bake for about 16 to 18 minutes until the crust is just starting to lightly brown.
• Remove and let cool.

Lemon curd

• Whisk together the granulated sugar, flour, and salt in a medium sized sauce pan, ideally one with sloped sides if you have one. Then beat in the eggs, lemon zest, and lemon juice.
  1 cup (200 grams) granulated sugar, ¼ cup (32 grams) all-purpose flour, ¼ teaspoon salt, 4 large eggs, zest of 3 lemons, ¾ cup fresh lemon juice
• Heat the sauce pan over medium low-heat, stirring constantly, for about 6 to 8 minutes until the curd starts to thicken and the temperature reaches 160℉ on an instant read thermometer if you have one. If the curd starts to steam, remove the pan from the burner and turn down the heat slightly.
• Remove the pan from the heat and stir in the softened butter. Once the butter has been incorporated, strain the curd on top of the graham cracker cookie crust and bake for 8 to 12 minutes until the curd has just set. It should still have a bit of jiggle.
  4 tablespoons (57 grams) unsalted butter
• Let the lemon bars cool in the pan. Cover and refrigerate if not serving immediately.

Lemon squares

• Cut your lemon bars into 16 two-inch lemon squares. Then dust with powdered sugar to serve, if you like.
  powdered sugar